Device for the structural closure and fastening of folders

ABSTRACT

This device for the structural closure and fastening of folders consists of a reciprocal set of coupling members and assembly, which, provided with insert fasteners and fixation members that are mounted on the edges of the covers, allow the closure of a filing folder which allows to close the filing folders adequately, while keeping their structural integrity and preventing deformations and breaks. It also allows the correction of the deformations in case they occurred.

The present invention claims priority of Argentina Patent ApplicationNo. P060103179 filed on Jul. 24, 2006.

FIELD OF THE INVENTION

The present invention refers to the field of temporary assembly of papersheets or any other laminar elements for their filing. Moreparticularly, it consists of a device for the structural closure andfastening of new or used ring binders, which allows to close the filingfolders adequately while it keeps their structural integrity preventingthe warping of new folders or the modification of the structure of usedfolders, allowing them to remain in a stable position when they arefiled vertically or horizontally.

BACKGROUND OF THE INVENTION

The ring binders for temporary assembly of paper sheets or any otherlaminar elements are known in the prior art. Said type of folder has acentral rectangular back or part from which the longest longitudinalrims, two covers are projected and a fastening mechanism which may beplaced on the back or on any of the covers by means of which the sheetscan be inserted, secured or removed quickly and easily.

Probably the most usual type of folder is the one that has a fasteningmechanism with two or three rings placed on the back or on any of thecovers, in this latter case, called back cover. The rings coincide withthe perforated holes on the sheets, which once inserted into them arefastened to the folder.

For more than 70 years, these folders have been manufactured withsystems that could not solve structural deficiencies, which make thefolders present difficulties to remain tidied and stable when they areplaced in vertical position and can overturn towards one side.

In several patents, another problem to be solved is presented, that isthe instability of the folders when they are piled up horizontally,because they slide one over the other, even when they are stackedalternately with their backs in opposite positions. The horizontalstacking of the folders is a filing manner used to save space when thefolders cannot be kept stable in vertical position, but this is not themanner to do it already considered for their use. The causes of thesemain problems, although not the only ones, are different in each case.

One of the reasons for the difficulty in keeping the folders tidy whenthey are in a vertical position, or that they cannot be stackedhorizontally without them sliding one over the other, is related withthe triangular shape adopted by the supporting base of the folder on ashelf, when the free ends of the covers tend to join. When severalfolders are placed vertically one beside the other, they adopt thisshape, although temporarily, and the whole set of folders has an untidyaspect and eventually, if one of them loses balance and overturns, therest of them can also overturn easily due to the “domino effect”.

A simple manner of reducing the chances of lateral overturning is tomake the covers of the folders remain substantially parallel. Thisproblem is stated in several patents and they present different types ofsolutions. In all cases, the inventors make the conclusion that thetriangular shape of the supporting base of the folders is mainly due tothe fact that they do not contain enough amount of filed sheets for thecovers to be substantially parallel. Consequently, according to someinventors, the way of solving the problem is to achieve parallelism ofthe covers regardless the amount of sheets filed.

Further to these considerations, the most relevant patents are thefollowing: GB2341140; CA2245452; U.S. Pat. No. 6,944,918; U.S. Pat. No.5,947,521; U.S. Pat. No. 5,380,111; U.S. Pat. No. 5,267,804; U.S. Pat.No. 5,002,416; U.S. Pat. No. 4,531,764; and NL1013926. Even though thesesolutions are successful to keep the covers parallel, thus solving theproblem of “untidy aspect” presented by the folders, neither of themsolves the problem of “vertical stability”. Although the cause of theuntidy aspect presented by the folders is related to the lack ofparallelism of the covers, this is not the main reason for the lack ofstability of the folders. They are problems, in a certain manner relatedto it, but the causes have different origins and therefore, requiredifferent solutions. Only when the folders contain very few pages, theproblem of stability can be solved partially, only getting that thecovers become substantially parallel.

The cause of the instability of the folder when it is filed verticallyis due to the fact that the position of the force resulting from all theforces applied, constituted by the own weight of the components and thestored sheets, is placed—depending on where the sheet fasteningmechanism is placed—in such a place that it produces a momentum ofvertical section (overturn) that cannot be counteracted by the folderstructure, in which the manner of transmitting the forces to thesupporting surface of the folder plays a key role.

The shape of the supporting surface of the folder is determined by theedges of both covers and the back of the folder which stand on the shelfand a fourth imaginary line which relates the free ends of the covers.The shape of the surface is variable depending on the relative positionof one cover respect to the other, which, in case the free ends of thecover touch each other, has the shape of an isosceles triangle with itsheight being 4 or 5 times longer than the width of the base.

Considering the height of the folders can be 4, 5 or 6 times longer thanthe widest part of the supporting triangular surface, that is the widthof the back, and that most of the force resulting from all the forcesapplied is physically related by means of the fastening mechanism, onlyto the back or to one of the covers with a leverage arm which increaseswith the amount of sheets stored, then, a momentum of overturn isproduced generally placed half way of the folder height, making itoverturn easily. This is due to the fact that the reaction forcesexerted—from downwards to upwards—by the supporting surface are mainlyapplied to the parts of the folder that do not contain the fasteningelement—free cover and/or back—, which make these parts move verticallyupwards relative to the part of the folder which contains the sheetfastening element—usually the back cover.

These relative movements between the back and the covers are due to thefact that, altogether, they form a structure where numerous points on ithave several degrees of freedom of movement. In addition, the abovementioned movements between the parts make the structure of the folderbe warped so that the position of the resulting force moves towards oneside until reaching a point where the center of gravity falls outsidethe supporting base of the folder and the latter overturns towards thatside. That is to say, a little movement of the cover upwards causes thestructure of the folder to warp, something that translates into asignificant movement of the original position of the resulting forces upthe cover favored by the height of the folder and the increase of storedsheets.

As the forces act permanently and increase in relation with the largeramount of stored sheets, the warping of the structure becomes permanentand irreversible. After a certain time of use, and even taking out allthe filed sheets, the folder remains deformed in such a manner that thevertical projection of the center of gravity may be easily placedoutside the supporting base even when the free ends of the covers do nottouch each other or are parallel.

The aforementioned shows that it is not necessary and not even enough tolook for keeping the covers in an almost parallel position to avoid theinstability problem, which is the most important of all the problemsthat may come up. To achieve parallelism of the folder covers, speciallywhen some of them are filed one next to the other—and only when they donot have their structures deformed—only causes an increase of theefficiency of the support or stand action when the folders are placedbetween two lateral devices that prevent them from overturning to oneside, in the same manner as with books on a bookshelf. Even though astanding surface of an almost rectangular shape favors stability, theshapes of said surfaces do not solve the instability problem, but thestructural deformations of the folder—related to the shape of thestanding surface—are the ones that have to be controlled to avoid theproblem.

Therefore, the conclusion is:

-   -   1. The problem related with “keeping the folders tidy”, when        they are vertically filed, is not necessarily related to the        problem of “keeping them stable”. Consequently, not necessarily        a solution to achieve parallelism is a sufficient solution to        keep the folder stable.    -   2. The difficulty for horizontal stacking of the folders should        not be posed as a problem to be solved as said action would not        be necessary to perform if a folder had the attribute of        remaining stable when it is filed vertically, which is the way        of using it already considered.

In the patents U.S. Des. 366,496; U.S. Pat. No. 5,695,295; U.S. Pat. No.5,634,666; U.S. Pat. No. 5,590,909; U.S. Pat. No. 5,348,971; U.S. Pat.No. 4,997,207; U.S. Pat. No. 4,744,689; U.S. Pat. No. 4,569,613; U.S.Pat. No. 4,524,991; GB2306395 and GB2079224, the problems of“untidiness” and “instability”, are posed in an indefinite, confuse,incomplete or wrong manner. Although the problem of instability iswrongly posed as a lack of parallelism of the covers, the solutionsshown offer a certain degree of solution to the problem of instability,but they show practical problems such as: outstanding in the outer partof the covers, placing and removing a device each time the folder isused, high manufacturing costs, not being able to be applied to usedfolders, being uncomfortable to use, having a weak construction, notallowing relocation as they have to be applied by means of adhesives ornot having good adaptation to the folder covers.

In the patents U.S. Pat. No. 5,897,141; U.S. Pat. No. 4,750,884;GB2341140; GB2286560 and CA2468476, the problem of instability is posedtaking into account some considerations of our analysis. The patentsU.S. Pat. No. 4,750,884 and GB234140 only reduce the consequences but donot solve the problem. Even though the patents U.S. Pat. No. 5,897,141,GB2286560 and CA2468476 partially solve the problem of instability; theproblem conceptualization led them to disclose solutions, whichoriginate products that are costly, large and complicated to handle.

The patent U.S. Pat. No. 2,804,872 discloses a partial solution to theproblem we posed, although it is incomplete when the folder reaches itsmaximum capacity of storage as the momentum of vertical section(overturn) cannot be counteracted effectively by the reaction forcecoming from the linking of the sheet fastening mechanism and the freecover. This reaction force is insufficient due to the location of thelinking point between the above-mentioned parts. This problem aggravateswhen the free cover of the folder suffered structural deformations. Inthis case, even when the fastening mechanism is inserted into the freecover slots, the folder can lose its stability easily. In fact, thedesign presented in the present patent is not a response to solve thestability problem, but to save space by manufacturing a folder having anarrower back. In addition, the design disclosed substantially improvesthe stability of the folders.

From the above, it can be stated that, in view of the manner of definingthe problem in the above mentioned patents, the solutions disclosed areinadequate or insufficient to solve the problem we have pointed out.Therefore, they should be considered as the closest background but notrelevant regarding our analysis and the solution disclosed herein.

Then, there is a need of a new device useful to solve the problem posed,preventing or reducing the structural deformations that may occur in newfolders or controlling the degree of deformation of the used folderstaking it to an adequate level to prevent them from losing the verticalstability. Once this problem is adequately solved, it is not necessaryto make the covers remain in a substantially parallel position to betidied and it is not necessary to make the folders stack horizontallyeither, as this requirement will not be necessary if they can remainstable in a vertical position.

The current needs require such a device to behave as if it were anintegral part of it and without degrees of freedom at the linking point;it should also be easy to place and remove; it should not come off incase of sudden handling and within certain limits; it should provide aneasy and simple opening and closure mode which does not interfere withthe access of the stored sheets; and it should not interfere with otherfolders placed next to it. As additional attributes, the device shouldkeep the covers substantially parallel and will allow the folders to bestacked horizontally in a stable manner in case they are piled up inthat way.

SUMMARY OF THE INVENTION

An objective of the present device is to relate the covers of a folderso that the structural deformation of the folder is prevented, thuspreventing it from losing the stability when it is filed vertically.Being a device with a very solid structure and with a link between itsparts and between the device and the folder covers where the movementfreedom is minimized, it is achieved that the device provides a rigiditybetween the covers that allows the momentum of vertical section appliedon the back cover to be transmitted efficiently and efficaciously to thefront cover.

In consequence, the device applies a downward force to the free cover,which avoids the deformations of the set cover-back-cover. Therefore,the device adopts a structural compensating behavior and equivalent tothe back situated at the part opposite the covers.

One of the advantages of the present device is that it can be applied tonew folders or in good use as well as to deformed folders. In the firstcase, it avoids the occurrence of deformations and in the second case;the correction of the structural deformation is achieved placing it inthe most suitable position by means of trial and error. Once it isplaced, it can be removed and placed in another position if thestructural compensation is not satisfactory for different amounts ofstored sheets.

Another advantage of the present device is that, due to its coupling andcramping means, it allows to open and close the covers without the needof removing or disassembling it, something that facilitates the use andprevents the deterioration of the folder edges.

A further advantage is that it allows a very good fastening of thecover, without movements or clearance that may hinder its structuralfastening function.

A further advantage is that the placement and removal are simple. Onceit is placed, it is difficult that it comes off accidentally.

Another advantage of the present device is that the insert fastenerscomprise some thin mechanically strong laminar metal clips that fastenthe outer part of the covers. Therefore, they outstand from the coversvery insignificantly. If we add the fact that the device has such a sizethat once it is placed on the folder, makes the separation between thecovers be shorter than the back width, both attributes help the devicenot to interfere with other adjacent folders and prevent that, upontaking the folder out of its place, it draws the neighbor folders andsome of them fall down.

Yet a further advantage is that the presence of positional anchors onthe fixation base allows varying the position of the clips and,therefore, adapts the insert fasteners to folders having differentthickness. In this manner, the link between the device and the foldercovers is optimized.

Another advantage is that the device is, at the same time, structurallystrong and light.

Another advantage is that the device, being structurally strong andbeing strongly fixed to the covers, allows stacking several foldershorizontally and in case of an accidental fall of one of them, thecovers do not open and the filed sheets cannot come out of the folder.

Another advantage is that the coupling means have been arranged in sucha manner that they prevent undesirable clearances or movements.

A further advantage is that the coupling means have been arranged insuch a manner that the opening of the covers is performed easily bymeans of the pressure exerted upon moving the thumb and the index fingeras pliers over the two flexible parts that unbind the device without theneed of using both hands.

Another advantage is that the front of the device has an area designedto apply a logo-type.

A further advantage is that the device can be detached from the folderand be placed on another folder.

Yet a further advantage is that the design allows a low costmanufacturing.

DESCRIPTION OF THE DRAWINGS

For the sake of better clearness and understanding of the invention, itis illustrated with several drawings in which it has been represented inone of its preferred embodiments, in an illustrative but not limitingmanner:

FIG. 1 is a perspective view of a decoupled device in accordance withthe present invention;

FIG. 2 is a perspective view of the fastening clip in accordance withthe present invention;

FIG. 3 is a perspective view of the coupled device in accordance withthe present invention;

FIG. 4 comprises drawings A, B and C, wherein Drawing 4A is an elevatedside view of the second coupling means; Drawing 4B, is an elevated backview of the second coupling means; and Drawing 4C, is an elevated frontview of the second coupling means in accordance with the presentinvention;

FIG. 5 comprises drawings A, B and C, wherein Drawing 5A, is an elevatedlateral view of the first coupling means; Drawing 5B, is an elevatedback view of the first coupling means; and Drawing 5C, is an elevatedfront view of the first coupling means in accordance with the presentinvention;

FIG. 6 is an elevated side view of both coupling means in decoupledposition in accordance with the present invention;

FIG. 7 is a longitudinal section of both coupling means in decoupledposition in accordance with the present invention;

FIG. 8 is another longitudinal section as in FIG. 7 where the positionof placement of the fixation screws is indicated in accordance with thepresent invention;

FIG. 9 is an elevated side view of a folder with the device placed andin decoupled position in accordance with the present invention;

FIG. 10 is an elevated side view of a detail from FIG. 9 in accordancewith the present invention;

FIG. 11 is an elevated side view of a folder with the device placed andcoupled, keeping the folder structurally stabilized in accordance withthe present invention; and

FIG. 12 is an elevated side view of a detail from FIG. 11.

In the different figures, the same referral numbers indicate equal orcorresponding parts, and the sets of several elements have been markedwith letters.

LIST OF THE MAIN REFERENCES

(1) Device for closure and structural fastening.

(2 a) First coupling means.

(2 b) Second coupling means.

(3) Coupling stop.

(4) First coupling body.

(5) Second coupling body.

(6) Fixation base [insert fastener].

(7) Contact wall [insert fastener].

(8) Anchorage opening [formed at the fixation base (6) for the fasteningclip (13) of insertion].

(8 a) First positional anchorage.

(8 b) Second positional anchorage.

(9) Fixation opening.

(9 a) Fixation duct.

(9 b) Fixation screw.

(10) Elastic cramping arms.

(10 a) Cramping head.

(11) Forced wedging cavity.

(11 a) Cramping edge.

(12) Cramping release arms.

(12 a) Cramping release terminal.

(13) Fastening clip [insert fastener].

(13 a) Fastening body.

(13 b) Anchorage body.

(13 c) Anchorage hole.

(14) Insert fastening cavity [formed between the fastening body (13 a)and the contact wall (7)].

(20) Filing folder.

(21) Back or central part.

(21 a) Longitudinal edges of the back (21).

(22) Fastening hooks.

(23) Covers.

(23 a) External edges of the covers (23).

(23 b) Inner faces or sides of the covers (23).

(23 c) Outer faces or sides of the covers (23).

DETAILED DESCRIPTION

In general terms, the present invention refers to a device for thestructural closure and fastening of folders that comprises a reciprocalset of coupling means (2 a)(2 b) which, provided with insert fasteners(6)(13) and fixation means (9)(9 a)(9 b) that are mounted on the edges(23 a) of the covers (23), allows the closure of a filing folder (20)keeping a structural fastening that prevents deformations or allows tocorrect them in case they occurred.

More particularly, the present device (1) is applicable to folders (20)for filing elements such as paper or plastic sheets, laminar elements ingeneral, envelopes, envelopes or cases to keep discs [CD's, DVD's,diskettes], etc. These filing folders (20), usually comprise a back (21)or central part in which an inner face has a set of fastening means orhooks (22) intended to insert the holes of the elements to be filed.From the longitudinal edges (21 a) of the back, (21) the mobile covers(23) project—towards both sides—and their mobility allows the openingand closure of the folder (20). Each cover (23) is limited by an outerface (23 c), an inner face (23 b) and external edges (23 a).

The present device (1) comprises a set of reciprocal coupling means (2a)(2 b) integrated by a first (2 a) and second (2 b) coupling meanswhich, in the present embodiment, are of the box and pin type. Thesecoupling means (2 a)(2 b) comprise a set of bodies (4)(5) which, as anelastic broach, are pluggable by means of the forced wedging until theassembly of an elastically releasable cramp (10 a)(11 a).

The first coupling means (2 a) comprises a first body (4) which, on theone hand, forms a fixation base (6) to the folder (20), whereas, on theother hand, has cramping elastic arms (10) which free ends form twocramping heads (10 a). These elements constitute the pin part of thecoupling.

The second coupling means comprises a second body (5) which, on the onehand, form a fixation base (6) to the folder (20), whereas, on theopposite part, forms a forced wedging cavity (11) which constitutes thebox part of the coupling.

At the bottom of the above-mentioned forced wedging cavity (11), thereare some cramping edges (11 a) intended to the cramping heads (10 a) ofthe first coupling means (2 a). Quite behind, there are some crampingreleasing terminals (12 a) which project from the elastically conveyingcramping releasing arms (12).

The forced wedging cavity (11) presents a progressive widening from theentrance or stop (3), so that said progressive widening constitutes acooperating means with the functionality of the coupling means (2 a)(2b) [when it couples, it gradually compresses the elastic cramping arms(10) and when it decouples, it cooperates with said decoupling].

On the other hand, both fixation bases (6) have a contact wall (7) thatcontacts the inner face (23 b) of the cover (23). This contact wall (7)can be provided with non-slip means such as, for instance, someprotruding embossments that can be sharpened so that their actionagainst the cover (23) prevents undesirable movements.

The fixation bases (6) also have anchorage openings where some fasteningclips (13) are anchored. The latter (13) can be comprised by elasticlaminar means [for example, they can be structured in resistant andelastically flexible metals].

In this manner, the contact wall (7) and the fastening clip (13)complement each other to form an insert fastener which fastening cavity(14) or wedge is prepared to receive the external edge (23 a) of thecover (23), on which they act as a fastening little claw.

The fastening clip (13) is folded so that a fastening sector or body (13a) and an anchorage sector or body is distinguished (13 b).

It has been provided that the anchorage body (13 b) of the fasteningclip (13) has a set of alternative positional anchorage means (8 a)(8b), which, as positional variation means, are situated in the anchorageopening (8) of the fixation base (6).

The anchorage body (13 b) also has an anchorage hole (13 c) to allow theaction of the fixation means (9)(9 a)(9 b) constituted [for example] byfixation screws (9 b) which, placed into fixation ducts (9 a) that crossthe fixation bases (6), are capable of projecting and exerting pressureon the part of the cover (23) able to be inserted in the fastening wedgeor cavity (14). Upon crossing the hole of the fastening clip (13), thefixation screws (9 b) also form part of the anchorage of said clip (13)in the fixation base (6).

Operation

To place the present device (1), the edges (23 a) of the covers (23) areinserted in the fastening cavity (14) of the insert fasteners formed bythe fixation bases (6) and the fastening clips (13). In theseconditions, the contact walls (7) remain attached to the inner faces (23b) of the covers (23), whereas the fastening bodies (13 a) of the clips(13) stay attached to the outer faces (23 c) of said covers (23) of thefolder (20).

The fixation screws (9 b) are placed in the fixation ducts (9 a) sothat, projecting themselves through the anchorage opening (8) of thefixation base (6) and through the anchorage holes (13 c) of thefastening clips (13), exert pressure on the part of the cover (23)inserted in the fastening cavity (14).

With the device (1) so arranged, the first coupling means (2 a) can beinserted in the second (2 b), with which, as a mode of elastic broach offorced wedging, said first means (2 a) enters until reaching thecoupling stop (3). This is possible because the elastic cramping arms(10) are bent by forced insertion and slip within the wedging cavity(11) until the heads (10 a) encase into the cramping edges (11 a) andsaid cramp is assembled.

In these conditions, the fastening and fixation exerted by the meansdescribed, keep the folder (20) structurally unaltered, preventing itsbending, folding or disassembling.

To disassemble the cramp, it is enough to press the releasing arms (12)which releasing terminals (12 a) move the cramping heads (10 a) fromtheir position against the cramping edges (11 a). When the cramp isreleased, the coupling means (2 a)(2 b) can be decoupled and the folder(20) can be opened.

It has been provided that the device (1) may have different sizes thatfacilitate its application to different types of folders (20). Forexample, that the separation between both insert fasteners (6)(13) isshorter than the width of the back (21) of the application folder (20).In this manner, the folder (20) can be kept adequately closed withoutthe covers (23) being arranged in a parallel manner.

1) A device for the structural closure and fastening of folders, whichis applicable to filing folders having: a back or central part on whichthe inner part includes fastening means of the elements to be filed andfrom which longitudinal edges project the mobile covers limited byexternal faces, inner faces and external edges; which comprises: a setof reciprocal coupling means; in said reciprocal coupling means, basisof fixation to the inner faces of the respective covers, components ofthe application folder; in each fixation base, insert fasteners preparedto serve as wedge for the edges of said covers; and fixation meanswhich, applicable to the inner faces of the covers, act in said fixationbases as a complement of said insert fasteners. 2) A device for thestructural closure and fastening of folders in accordance with claim 1,which comprises a set of reciprocal coupling means of the box and pintype. 3) A device for the structural closure and fastening of folders inaccordance with claim 1, wherein said coupling means comprise, at least,a set of pieces that, as an elastic broach, are connected by means offorced wedging to provide the assembly of an elastically releasablecramp. 4) A device for the structural closure and fastening of foldersin accordance with claim 1, wherein the elastically releasable cramp isdouble. 5) A device for the structural closure and fastening of foldersin accordance with claim 3, wherein said elastically releasable crampcomprises cramping releasing means capable of moving its assemblyposition to each cramping means. 6) A device for the structural closureand fastening of folders in accordance with claim 1, wherein saidfixation bases comprise respective contact walls with the cover providedwith non-slip means. 7) A device for the structural closure andfastening of folders in accordance with claim 6, wherein said non-slipmeans comprise protruding embossments. 8) A device for the structuralclosure and fastening of folders in accordance with claim 6, whereinsaid non-slip means comprise sharpened protruding embossments. 9) Adevice for the structural closure and fastening of folders in accordancewith claim 1, wherein each fixation base, the insert fastener iscomprised by the contact wall and at least a clip, being said contactwall and said clip arranged in such a manner that they complement eachother in the assembly of a wedge prepared to receive the edge of afolder cover. 10) A device for the structural closure and fastening offolders in accordance with claim 1, wherein said clip is an elasticlaminar means which has anchorage means in the fixation base. 11) Adevice for the structural closure and fastening of folders in accordancewith claim 9, wherein said clip is an elastic laminar means which has aset of alternative anchorage means that enable its positional variationin the fixation base. 12) A device for the structural closure andfastening of folders in accordance with claim 9, wherein said clip is anelastic laminar means that, faced with the fixation base, comprises afastening little claw applicable to the application folder cover. 13) Adevice for the structural closure and fastening of folders in accordancewith claim 9, wherein said clip is an elastic laminar means constitutedby a steel strip. 14) A device for the structural closure and fasteningof folders in accordance with claim 1, wherein said fixation meanscomprise screws that, passing through the fixation base, are capable ofprojecting and exerting pressure on the part of the cover which insertsinto the wedge. 15) A device for the structural closure and fastening offolders in accordance with claim 14, wherein said fixation meanscomprise screws that, in addition to passing through the fixation basewith a capacity to project and exert pressure over the part of the coverthat inserts into the wedge, also pass through the clip so that theyform the anchorage of said clip in said fixation base. 16) A device forthe structural closure and fastening of folders in accordance with claim1, wherein said active coupling means determine that the separationbetween both insert fasteners is shorter than the width of the back ofthe application folder. 17) A device for the structural closure andfastening of folders in accordance with claim 2, in which the boxcoupling means comprises an insert cavity with a progressive wideningfrom the entrance of said cavity, so that said progressive wideningconstitutes a cooperating means with the functionality of the couplingmeans.